Android :: How To Switch From Activity To ListActivity?

This post probably shows my ignorance of Android coding, but here goes. I have a sample app I am developing which starts by extending Activity. I have a main.XML layout which works great. On a button click from the main layout I'd like to load a ListView. I think I understand how to use ListView and seed data into it. I have created a new layout which contains this ListView. I am confused, however, how I switch from a regular Activity to a ListActivity so I get the convenience methods like setListAdapter()? Should I be starting with a ListView, and then drawing the other view on top once the app starts by inflating the layout and using it? If not, how do I create a ListActivity object inside my app, and where should I create that? If you have a sample application or tutorial that shows how to do this, I would appreciate it.